21st week of pregnancy

  • Biparietal diameter of foetus: 49 to 59 mm
  • Weight of foetus: approx. 410 g

Some women can now from time to time feel a painless hardening of the uterus. These are only premonitory pains and are harmless exercises for the body. If these contractions happen often, regularly and are painful, you should inform your gynaecologist. They might be early labour pains.


The skin of your child becomes thicker and reddish. It is covered with a fine fluff, the lanugo hair, which both protects and regulates body temperature. This hair usually disappears during the 9th month of pregnancy, which is considered at the time birth to be a sign of maturity.


A whitish waxy layer covers the whole body of your baby, the vernix caseosa. It protects the skin from getting soaked by the amniotic liquid. Most of the vernix caseosa will have disappeared by the time of birth.


Most babies open their eyes at about this time, and the eyelids already have lashes. But because it is so dark in the womb, eyesight is not very well trained before birth. The nostrils are open as well, and its small heart beats about 150 times a minute, transporting about 100 litres of blood per day. The foetus is able to make breathing movements, swallow, cough and suck its thumb.


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